Many active substances (i.e. therapeutic ingredients) of medicines have poor solubility in water; with such substances, the absorbability from the alimentary canal is low, and hence the utilizability, the expression of therapeutic effects and so on are prone to dropping or fluctuating. In preclinical trials, when searching for therapeutic effects or biopharmaceutical parameters in animals or the like, it is common to make the therapeutic ingredient more easily absorbable by dissolving it in some kind of solvent; for a sparingly soluble therapeutic ingredient, polyethylene glycol of relatively low molecular weight or a derivative thereof, a polyoxyethylene sorbitan fatty acid ester, a fatty acid having 6 to 12 carbon atoms or a salt thereof, polyoxyethylene castor oil, a derivative of diethylene glycol, or the like is used. However, these solvents are generally liquids, and hence making tablets is difficult, and moreover the pharmaceutical form ultimately put onto the market is developed separately. If these solvents could be made into a pharmaceutical preparation directly, then the time required for making the pharmaceutical preparation could be greatly reduced; the most promising pharmaceutical form for this is a capsule. However, there is a drawback in that if a conventional gelatin hard capsule is filled with polyethylene glycol having a degree of polymerization of 400 (PEG 400), then moisture in the capsule skin migrates into the solvent, and the capsule may split (Pharmaceutical Technology Europe, Oct., 84, 86, 88-90, 1998). Moreover, with a conventional cellulose derivative capsule, the above solvents act as plasticizers, and hence a so-called ‘sweating’ phenomenon occurs on the surface of the capsule in which the solvent permeates through the capsule skin.